package 蓝桥真题;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class 刷题统计 {
       static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
       static long a,b,n;
       
       public static void main(String[] ss) throws IOException {
		      ss=br.readLine().split(" ");
		      a=Long.parseLong(ss[0]);b=Long.parseLong(ss[1]);n=Long.parseLong(ss[2]);
		      long res=n/(5*a+2*b)*7;
		      n=n%(5*a+2*b);
		      for(int i=1;i<=5;i++){
		    	  if(n<=0)break;
		    	  n=n-a;
		    	  res++;
		      }
		      for(int i=1;i<=2;i++){
		    	  if(n<=0)break;
		    	  n=n-b;
		    	  res++;
		      }
		      System.out.print(res);
	}
}
